class Solution {
public:
    int uniquePaths(int m, int n) {
    	if (!m || !n)
    		return 0;
        int path[m][n];
        for (int i = 0; i < n; ++i){
        	path[0][i] = 1;
        }
        for (int i = 0; i < m; ++i){
        	path[i][0] = 1;
        }
        for (int i = 1; i < m; ++i){
        	for (int j = 1; j < n; ++j){
        		path[i][j] = path[i-1][j] + path[i][j-1];
        	}
        }
        return path[m-1][n-1];
    }
};